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arXiv:2509.02629

\textit{In Silico} Benchmarking of Detectable Byzantine Agreement in Noisy Quantum Networks

Bhatia, Mayank, Doshi, Shaan, Daniel Winton, Brian Doolittle, Bruno Ricardi de Abreu, Santiago Núñez-Corrales

Published Sep 1, 2025• 0 citations
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Abstract

Quantum communication resources offer significant advantages for fault-tolerant distributed protocols, particularly in Byzantine Agreement (BA), where reliability against adversarial interference is essential. Quantum Detectable Byzantine Agreement (QDBA) enables consensus protocols that surpass classical limitations by leveraging entangled quantum states. In this work, we focus on the practical realization of QDBA using Einstein-Podolsky-Rosen (EPR) pairs, the simplest maximally entangled quantum resources, making the protocol experimentally accessible across current quantum hardware platforms. We present a comprehensive computational study of the EPRQDBA protocol under realistic quantum network conditions, utilizing the Aliro Quantum Network Simulator to evaluate the performance and robustness of the protocol. Our simulations systematically explore the protocol's parameter space --including variations in network size, traitorous node count, the amount of entanglement consumed in the protocol, and physically motivated noise models tailored specifically for superconducting and photonic qubit technologies. Through extensive numerical experiments, we provide insights into how these physically realistic parameters impact protocol performance, establishing critical thresholds and optimal operational regimes for experimental implementations. This work bridges theoretical advances in quantum consensus protocols with practical network implementations, offering a concrete reference for experimentalists. Our findings serve as a guideline for evaluating and optimizing QDBA implementations in realistic, noisy environments.

DOI
10.48550/arxiv.2509.02629

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In distributed quantum computing (DQC), achieving consensus with adversarial elements presents a critical challenge. This paper proposes an innovative framework that enhances the Quantum Byzantine Agreement (QBA) protocol by integrating practical quantum error mitigation techniques, specifically Quantum Readout Error Mitigation (QREM) and Dynamical Decoupling (DD). Utilizing Noisy Intermediate-Scale Quantum (NISQ) devices, our approach aims to improve operational reliability significantly. Our results demonstrate that QREM and DD effectively mitigate common quantum channel errors through rigorous experimentation on both simulated environments and IBM’s quantum hardware. The proposed protocol also introduces a verification mechanism inspired by Quantum Key Distribution (QKD) systems, ensuring the secure transmission of commands encoded in quantum states. In cases of discrepancies, lieutenants engage in systematically designed interactions to achieve consensus, influenced by the Commander’s strategic decisions and the network’s size. Our empirical analysis highlights the protocol’s enhanced resilience and efficiency under various conditions, while also addressing challenges related to scalability as the network size increases.
Quantum entanglement can be employed in some distributed communication tasks to reduce computation and communication overheads, yielding speedups over their classical counterparts. However, existing quantum Byzantine protocols often entail excessive communication and entanglement resource consumption. Conversely, classical schemes face insecurity with the impending reality of quantum computers. To address these challenges, we present a novel quantum Detectable Weak Byzantine Agreement (DWBA) protocol with high practicability, security and optimal fault-tolerance bound. For all n players, our protocol can complete the consensus of infinite classical information via fixed n + 1 -entangled qubits and a digest function, which requires infinite entanglement resources in previous schemes. Moreover, our protocol can tolerate arbitrary t ( t < n ) faulty players without necessitating any additional initial setup information (e.g., digital signature, private random coins). In terms of efficiency, our protocol only requires O (1) rounds and O ( ( n − t ) 2 ) communication complexity, constituting an order of magnitude improvement over previous protocols. In addition, the DWBA problem solved by our protocol is inherently stronger than the 3-player Detectable Byzantine Agreement (DBA) problem solved by previous protocols, and in a weaker but sufficiently practical model, our protocol can achieve Weak Byzantine Agreement (WBA).
This paper presents a novel approach to distributed consensus protocols leveraging quantum entanglement and Byzantine fault tolerance. The core claim is that quantum entanglement can provide secure and efficient agreement among nodes even in the presence of malicious actors. We propose a mechanism that utilizes quantum key distribution (QKD) to establish shared entanglement between participating nodes. Subsequent quantum measurements identify faulty nodes, informing a robust consensus algorithm built upon majority voting and entanglement-based error correction. The potential advantages of this combined approach – enhanced security and efficiency compared to traditional classical methods – are explored. The research addresses the critical challenge of achieving reliable consensus in distributed systems susceptible to Byzantine attacks. This work introduces a new paradigm for consensus, potentially leading to more resilient and secure distributed applications.
Quantum Byzantine agreement (QBA), a cornerstone of quantum blockchain, offers inherent advantages in security and fault tolerance over classical protocols, guaranteed by the laws of quantum mechanics. However, existing multiparty QBA protocols face challenges for large-scale deployment due to exponential communication complexity or reliance on complex multi-particle entanglement. To address this, we propose a multiparty circular QBA protocol that adopts a semi-decentralized architecture, leveraging circular message gathering and quantum digital signatures to achieve quadratic communication complexity and enhanced fault tolerance. Our protocol is experimentally feasible, requiring only weak coherent states, and is compatible with existing star-shaped quantum networks. Simulations conducted on a global satellite-to-ground network demonstrate that the protocol sustains high consensus rates among multiple users, even when employing different key generation protocols under realistic conditions. This work presents a scalable framework for large-scale QBA networks, establishing the foundation for a practical quantum blockchain that enables secure and fault-tolerant decentralized services.
This paper proposes a novel distributed consensus algorithm utilizing quantum entanglement to achieve Byzantine fault tolerance. Traditional consensus algorithms struggle to guarantee correctness in the face of malicious actors (Byzantine faults) where nodes can arbitrarily deviate from the honest majority. This work introduces a protocol that leverages the unique properties of quantum entanglement to establish correlated states between nodes, enabling the detection and mitigation of these malicious behaviors without relying on trusted third parties or computationally intensive verification processes. The core claim is that quantum entanglement provides a provably secure and efficient mechanism for distributed consensus, offering superior resilience compared to classical approaches. The algorithm is formally described, and key mathematical components, including state transformations and probability calculations, are presented. The theoretical analysis demonstrates the algorithm's ability to converge to a correct consensus state even when a significant fraction of nodes are faulty. The use of entanglement fundamentally alters the Byzantine fault tolerance landscape, offering a pathway towards more robust and secure distributed systems.